ALBERT

Description: With the increasing anthropogenic impacts on fish habitats, it has become more important to understand which primary resources sustain fish populations. This resource utilization can differ between fish life stages, and individuals can migrate between habitats in search of resources. Such lifetime information is difficult to obtain due to the large spatial and temporal scales of fish behavior. The otolith organic matrix has the potential to indicate this resource utilization and migration with δ13C values of essential amino acids (EAAs), which are a direct indication of the primary producers. In a proof-of-concept study, we selected the Acoupa weakfish, Cynoscion acoupa, as a model fish species with distinct ontogenetic migration patterns. While it inhabits the Brazilian mangrove estuaries during juvenile stages, it moves to the coastal shelf as an adult. Thus, we expected that lifetime resource utilization and migration would be reflected in δ13CEAA patterns and baseline values in C. acoupa otoliths. By analyzing the C. acoupa otolith edges across a size range of 12–119 cm, we found that baseline δ13CEAA values increased with size, which indicated an estuarine to coastal shelf distribution. This trend is highly correlated with inorganic δ13C values. The δ13CEAA patterns showed that estuarine algae rather than mangrove-derived resources supported the juvenile C. acoupa populations. Around the juvenile size of 40 cm, resource utilization overlapped with those of adults and mean baseline δ13CEAA values increased. This trend was confirmed by comparing otolith core and edges, although with some individuals potentially migrating over longer distances than others. Hence, δ13CEAA patterns and baseline values in otoliths have great potential to reconstruct ontogenetic shifts in resource use and habitats. The insight could aid in predictions on how environmental changes affect fish populations by identifying the controlling factors at the base of the food web.

Description: With the increasing anthropogenic impacts on fish habitats, it has become more important to understand which primary resources sustain fish populations. This resource utilization can differ between fish life stages, and individuals can migrate between habitats in search of resources. Such lifetime information is difficult to obtain due to the large spatial and temporal scales of fish behavior. The otolith organic matrix has the potential to indicate this resource utilization and migration with δ13C values of essential amino acids (EAAs), which are a direct indication of the primary producers. In a proof-of-concept study, we selected the Acoupa weakfish, Cynoscion acoupa, as a model fish species with distinct ontogenetic migration patterns. While it inhabits the Brazilian mangrove estuaries during juvenile stages, it moves to the coastal shelf as an adult. Thus, we expected that lifetime resource utilization and migration would be reflected in δ13CEAA patterns and baseline values in C. acoupa otoliths. By analyzing the C. acoupa otolith edges across a size range of 12–119 cm, we found that baseline δ13CEAA values increased with size, which indicated an estuarine to coastal shelf distribution. This trend is highly correlated with inorganic δ13C values. The δ13CEAA patterns showed that estuarine algae rather than mangrove-derived resources supported the juvenile C. acoupa populations. Around the juvenile size of 40 cm, resource utilization overlapped with those of adults and mean baseline δ13CEAA values increased. This trend was confirmed by comparing otolith core and edges, although with some individuals potentially migrating over longer distances than others. Hence, δ13CEAA patterns and baseline values in otoliths have great potential to reconstruct ontogenetic shifts in resource use and habitats. The insight could aid in predictions on how environmental changes affect fish populations by identifying the controlling factors at the base of the food web.

Description: With the increasing anthropogenic impacts on fish habitats, it has become more important to understand which primary resources sustain fish populations. This resource utilization can differ between fish life stages, and individuals can migrate between habitats in search of resources. Such lifetime information is difficult to obtain due to the large spatial and temporal scales of fish behavior. The otolith organic matrix has the potential to indicate this resource utilization and migration with δ13C values of essential amino acids (EAAs), which are a direct indication of the primary producers. In a proof-of-concept study, we selected the Acoupa weakfish, Cynoscion acoupa, as a model fish species with distinct ontogenetic migration patterns. While it inhabits the Brazilian mangrove estuaries during juvenile stages, it moves to the coastal shelf as an adult. Thus, we expected that lifetime resource utilization and migration would be reflected in δ13CEAA patterns and baseline values in C. acoupa otoliths. By analyzing the C. acoupa otolith edges across a size range of 12–119 cm, we found that baseline δ13CEAA values increased with size, which indicated an estuarine to coastal shelf distribution. This trend is highly correlated with inorganic δ13C values. The δ13CEAA patterns showed that estuarine algae rather than mangrove-derived resources supported the juvenile C. acoupa populations. Around the juvenile size of 40 cm, resource utilization overlapped with those of adults and mean baseline δ13CEAA values increased. This trend was confirmed by comparing otolith core and edges, although with some individuals potentially migrating over longer distances than others. Hence, δ13CEAA patterns and baseline values in otoliths have great potential to reconstruct ontogenetic shifts in resource use and habitats. The insight could aid in predictions on how environmental changes affect fish populations by identifying the controlling factors at the base of the food web.

Description: With the increasing anthropogenic impacts on fish habitats, it has become more important to understand which primary resources sustain fish populations. This resource utilization can differ between fish life stages, and individuals can migrate between habitats in search of resources. Such lifetime information is difficult to obtain due to the large spatial and temporal scales of fish behavior. The otolith organic matrix has the potential to indicate this resource utilization and migration with δ13C values of essential amino acids (EAAs), which are a direct indication of the primary producers. In a proof-of-concept study, we selected the Acoupa weakfish, Cynoscion acoupa, as a model fish species with distinct ontogenetic migration patterns. While it inhabits the Brazilian mangrove estuaries during juvenile stages, it moves to the coastal shelf as an adult. Thus, we expected that lifetime resource utilization and migration would be reflected in δ13CEAA patterns and baseline values in C. acoupa otoliths. By analyzing the C. acoupa otolith edges across a size range of 12–119 cm, we found that baseline δ13CEAA values increased with size, which indicated an estuarine to coastal shelf distribution. This trend is highly correlated with inorganic δ13C values. The δ13CEAA patterns showed that estuarine algae rather than mangrove-derived resources supported the juvenile C. acoupa populations. Around the juvenile size of 40 cm, resource utilization overlapped with those of adults and mean baseline δ13CEAA values increased. This trend was confirmed by comparing otolith core and edges, although with some individuals potentially migrating over longer distances than others. Hence, δ13CEAA patterns and baseline values in otoliths have great potential to reconstruct ontogenetic shifts in resource use and habitats. The insight could aid in predictions on how environmental changes affect fish populations by identifying the controlling factors at the base of the food web.

Description: The Pacific region of Colombia, like many sparsely populated places in developing countries, has been imagined as empty in social terms, and yet full in terms of natural resources and biodiversity. These imaginaries have enabled the creation of frontiers of land and sea control, where the state as well as private and illegal actors have historically dispossessed Afro-descendant and indigenous peoples. This paper contributes to the understanding of territorialisation in the oceans, where political and legal framings of the sea as an open-access public good have neglected the existence of marine social processes. It shows how Afro-descendant communities and non-state actors are required to use the language of resources, rather than socio-cultural attachment, to negotiate state marine territorialisation processes. Drawing on a case study on the Pacific coast of Colombia, we demonstrate that Afro-descendant communities hold local aquatic epistemologies, in which knowledge and the production of space are entangled in fluid and volumetric spatio-temporal dynamics. However, despite the social importance of aquatic environments, they were excluded from Afro-descendants' collective territorial rights in the 1990s. Driven by their local aquatic epistemologies, coastal communities are reclaiming authority over the seascape through the creation of a marine protected area. We argue that they have transformed relations of authority at sea to ensure local access and control, using state institutional instruments to subvert and challenge the legal framing of the sea as an open access public good. As such, this marine protected area represents a place of resistance that ironically subjects coastal communities to disciplinary technologies of conservation.

Description: 〈jats:title〉Abstract〈/jats:title〉〈jats:p〉Plattentektonik, vulkanische Aktivität und Spreizung des Ozeanbodens in der Arktis: Die Emmy Noether‐Gruppe MOVE gewinnt nach aufwendigen Forschungs‐expeditionen und Erdbebenmessungen überraschende Erkenntnisse zur Entstehung und Struktur der Ozeanlithosphäre. Ein Werkstattbericht〈/jats:p〉

Description: Upper‐plate normal faults are a widespread structural element in erosive plate margins. Increasing coverage of marine geophysical data has proven that similar features also exist in accretionary margins where horizontal compression usually results in folding and thrust‐faulting. There is a general lack of understanding of the role and importance of normal faulting for the structural and tectonic evolution of accretionary margins. Here, we use high‐resolution 2D and 3D seismic reflection data and derived seismic attributes to map and analyze upper‐plate normal faulting in the marine forearc of the accretionary Hikurangi margin, New Zealand. We document extension of the marine forearc over a wide area along the upper continental slope. The seismically imaged normal faults show low vertical displacements, high dip angles, a preference for landward dip and often en echelon patterns. We evaluate different processes, which may cause the observed extension, including (1) stress change during the earthquake cycle, (2) regional or local uplift and decoupling of shallow strata from compression at depth, as well as (3) rotation of crustal blocks and resulting differential stresses at the block boundaries. The results suggest that normal faults play an important role in the structural and tectonic evolution of accretionary margins, including the northern Hikurangi forearc.

Description: Atlantic Warm Pool (AWP) climate variability is subject to multiple influences of remote and local forcing. However, shortage of observational data before the mid‐20th century and of long‐term sea surface temperature (SST) and climate records has hampered the detection and investigation of decadal‐ and longer‐scale variability. We present new seasonally resolved 125‐year records of coral δ18O and Sr/Ca variations in the Central Caribbean Sea (Little Cayman, Cayman Islands; Diploria strigosa). Both geochemical proxies show decreasing long‐term trends, indicating long‐term warming. Sr/Ca indicates much stronger regional warming than large‐scale grid‐SST data, while δ18O tracks large‐scale SST changes in the AWP. Seawater δ18O variations are reconstructed, indicating a drying trend over the past century. High spatial correlation between coral δ18O and SST in the region of the Loop Current and Gulf Stream system suggests that Little Cayman is a sensitive location for detecting past large‐scale temperature variability beyond the central Caribbean region. More specifically, our δ18O data tracks changes in North Atlantic Oscillation (NAO) variability on decadal and multidecadal time scales providing insights into the temporal and spatial nonstationarity of the NAO. A combination of our δ18O record with two coral records from different Caribbean sites reveals high spatial correspondence between coral δ18O and SST variability in the North Atlantic subtropical gyre, where few instrumental measurements and proxies are available prior to the 20th century. Our results clearly demonstrate the potential of combining proxy data to provide information from sparsely sampled areas, helping to reduce uncertainty in model‐based projections.

Description: Climate models generally underestimate the pronounced warming in the sea surface temperature (SST) over the North Atlantic during the mid‐Pliocene that is suggested by proxy data. Here we investigate the influence of the North Atlantic cold SST bias, which is observed in many climate models, on the simulation of mid‐Pliocene surface climate in a series of simulations with the Kiel Climate Model. A surface freshwater‐flux correction is applied over the North Atlantic, which considerably improves simulation of North Atlantic Ocean circulation and SST under present‐day conditions. Using reconstructed mid‐Pliocene boundary conditions with closed Bering and Arctic Archipelago Straits, the corrected model depicts significantly reduced model‐proxy SST discrepancy in comparison to the uncorrected model. A key factor in reducing the discrepancy is the stronger and more sensitive Atlantic Meridional Overturning Circulation and poleward heat transport. We conclude that simulations of mid‐Pliocene surface climate over the North Atlantic can considerably benefit from alleviating model biases in this region.